Thin film deposition method for ZnO nanosheets using low-temperature microwave-excited atmospheric pressure plasma jet

Highlights: • Microwave-excited atmospheric pressure plasma jet fabrication of ZnO nanosheets. • Low temperature growth of ZnO nanosheets. • ZnO nanosheets used as an electron collection layer in organic photovoltaic cells. • Enabled simple thin-film fabrication for low-cost mass production. -- Abstract: Electronic devices such as solar cells and thin-film transistors can be fabricated using thin-film deposition. Low-cost, low-temperature and high-speed deposition methods are required to ensure that the production of devices using thin-film deposition is affordable. Herein, we report the development of a low-cost and simple thin-film deposition method using microwave-excited atmospheric pressure plasma jet (MWAPPJ). MWAPPJ produces a low-temperature (several hundred degrees) plasma under atmospheric conditions, does not require expensive vacuum equipment, and it enables high-speed deposition of thin-films. Zinc acetylacetonate sol-gel precursors that were adhered to stainless steel mesh targets were irradiated by MWAPPJ with oxygen, which resulted in zinc oxide (ZnO) nanosheet thin-films with diameters of 100–200 nm on silicon substrates. We used 50-nm-thick ZnO thin-films that were processed using MWAPPJ as the electron collection layer in organic photovoltaic (OPV) cells. This work represents an important contribution to the design and production of low-cost OPV solar cells.